ViiV Healthcare's investigational HIV therapy dolutegravir is as effective as Merck & Co's Isentress (raltegravir), according to a phase III head-to-head study.
ViiV, a joint venture between GlaxoSmithKline (GSK) and Pfizer, is co-developing dolutegravir with Japanese pharma company Shionogi. The once-daily integrase inhibitor aims to prevent the HIV virus from entering an individual's immune cells, stopping its replication process.
The drug's once-daily treatment regimen could give it the edge over Merck's Isentress, which is also an integrase inhibitor but has to be taken twice-daily, now that both drugs have been shown to be similarly safe and effective.
The data comes from the SPRING-2 study, which demonstrated that after 48 weeks, 88 per cent of study participants on dolutegravir were able to suppress to virus compared to 85 per cent of participants on Isentress. Both treatments were given along with two nucleoside reverse transcriptase inhibitors (NRTIs).
The primary endpoint of virological suppression was the proportion of study participants with undetectable HIV-1 RNA through 48 weeks.
The study, which involved 822 treatment-naïve participants, also found tolerability for the two drugs was comparable, with rates of adverse events and nausea similar in both trial arms.
Trial data from three more phase III studies involving dolutegravir are expected in 2012, which GSK said will allow "further determination" of the drug's profile.
“This marks an important milestone for the development of dolutegravir and the Shionogi-ViiV Healthcare joint venture,” said Dr Tsutae Nagata, chief medical officer, Shionogi.
“We look forward to completing further phase III studies in a variety of clinical settings in order to fully understand the potential clinical benefit for a range of HIV patient populations.”
If approved, analysts have said that ViiV's drug could have revenues of more than $1bn a year, with patients and healthcare professionals preferring its simpler once-daily dosing formula. Isentress made $1.36bn for Merck during 2011.